The hypothesis to be tested in the proposed experiments is that the levels of gonadal steroids to which males are exposed during fetal life play a major role in determining the normal functioning of, and incidence of pathology in, prostate and coagulating glands as well as fertility during aging in male mice (Mus domesticus). Preliminary studies have shown that male mice with slightly elevated serum estradiol (E2) during fetal life have enlarged prostates, the greatest number of prostatic androgen receptors, and the highest rates of sexual behavior in adulthood. In contrast, exposure to a high (pharmacological) dose of E2 during fetal life has exactly the opposite effect on prostate weight and androgen receptors. The effects of estrogen exposure during fetal life on male accessory reproductive organs is thus dose dependent. Our experimental procedure involves treating pregnant females with a range of doses of E2 during the last third of pregnancy, and preliminary studies have been completed to determine the doses which increase serum E2 in male fetuses from 50-500% relative to untreated males. We will also administer a dose of testosterone (T) which elevates serum T in male fetuses by 50%, due to a surprising preliminary finding that this leads to a marked decrease in prostate weight in adulthood. Males from each prenatal treatment group will be examined in young adulthood, middle age and old age when gonadally intact or after castration/ adrenalectomy and replacement of gonadal steroids to control for any potential effects of prenatal treatment on gonadal steroid levels. Enzyme activity, fertility, sperm numbers in testes and epididymides, and both androgen and estrogen receptor numbers in prostate and coagulating glands will be examined. Regional heterogeneity of these organs will be assessed by conducting morphometric analysis coupled with in situ hybridization histochemistry (ISHH) for androgen and estrogen receptor mRNA's; these studies will use sections from the same organs. In addition to examining organs from young adult, middle aged, and old males, tissue will also be collected for morphometric and ISHH analysis during the fetal period of differentiation of prostate and coagulating glands.